1. Field of the Invention
The present invention relates to a railway train control system, and more particularly to a train thrusting electric current supply system for a railway system. More specifically, the present invention pertains to an electric current supply system having electric power control means provided as a ground facility.
2. Description of the Prior Art
In conventional electrically powered railway systems, electric power is supplied from a feeder wire to a train through collector shoes. The train has one or more motors, and controllers are provided on the train for adjusting the power supply to the motors so that the operation of the train is controlled in accordance with the intention of the train operator. Since the controllers are bulky and heavy, the conventional designs are considered disadvantageous in that the train always carries such bulky and heavy controllers.
In order to eliminate the problems, there is proposed in the Japanese patent application No. 57-131236 ;filed on July 29, 1982 and disclosed for public inspection on Feb. 7, 1984 under the disclosure number 59-23736 discloses a train system wherein the electric power controllers are provided as a ground facility and a controlled electric power is supplied to the train. According to the proposal, the power feeder line is divided into a plurality of sections each adapted for supplying electric power to a single unit of train. The operator on the train can apply a control signal to the controller provided on the ground and the controller provides a motor driving power which is controlled in accordance with the control signal from the train.
The train system as proposed by the above Japanese patent application is advantageous in that the overall weight of the train can be remarkably decreased. It should however be noted that, in this system, safety security provisions such as control signal lights have to be made as in the conventional systems in order to prevent accidents such as collisions of trains.
Similar train system is also proposed by the Japanese patent application No. 58-181334 filed on Sept. 29, 1983 and disclosed for public inspection on Apr. 23, 1985 under the disclosure number 60-71368. In this system, the ground facility includes an operation command device which provides operation command signals to the controller. The system as proposed by this Japanese patent application is however considered disadvantageous in that each spacing between adjacent two stations constitute a single unit of power feed section so that it is impossible to make two or more trains run in a single spacing between the two adjacent stations. Further, it is required to provide safety security provisions for preventing car collisions.
It may be possible to control the power supply to the power feed sections so that the power supply to one section is interrupted for the purpose of preventing car collisions. It should however be noted that this solution is not recommendable because a train cannot be started until a preceding train leaves the train which is ahead of the first mentioned train so that a longer interval is required between succeeding trains.
Recently, there is an increasing tendency to use three-phase AC motors for traction of railway trains because the AC motors are simple in structure and convenient for maintenance. For controlling operations of the train, at least one of the frequency, the phase and the voltage of the three-phase AC power is regulated. When the train systems of the aforementioned Japanese patent applications are power by AC, special measures have to be taken for the power supply to the train at junctions of the power feeding sections, however, there is no practical solution in the proposed systems.
It should further be noted that in the railway system wherein the controlled power is supplied from the ground equipment to the train, there is a danger that the operation of the whole system is stopped simply by a failure in the ground equipment. However, no solution is given by the aforementioned Japanese patent applications. Back-up systems may be provided for covering the ground equipment under failure. For example, a pair of equivalent equipments may be provided in parallel so that only one is used at a time and the other may be operated when the one equipment fails. However, such back-up systems are usually very expensive because unused facilities must in advance be provided. It may be possible to provide a power supply to a power feed section in case of a failure in the ground facility from another ground facility which is adjacent to the failed ground facility. However, in order to make such back-up possible, the ground facilities must be of large capacities so that an increased investment is required.